How to handle DMARC failures when email is forwarded by recipients?

Handling DMARC failures due to email forwarding requires a multi-faceted approach encompassing technical solutions, policy adjustments, and user education. A foundational step is to implement and rigorously maintain SPF, DKIM, and DMARC across all email domains to establish a baseline level of authentication and security. Starting with a DMARC policy of 'p=none' allows for monitoring and analysis of email streams without rejecting legitimate emails, enabling the identification of forwarding patterns and authentication issues. The Authenticated Received Chain (ARC) protocol emerges as a pivotal technology, preserving authentication results across intermediaries and thus validating the original authentication even after forwarding, though it's not a complete solution. Recipient education on proper forwarding techniques, such as forwarding as attachments, and offering alternative communication methods like SMS notifications mitigate authentication failures. Other technical considerations include SPF flattening to avoid exceeding lookup limits, and configuring trusted forwarders in Microsoft 365. Regular audits of email infrastructure, coupled with reviewing DMARC reports, ensure ongoing effectiveness.

When handling DMARC failures due to email forwarding, several strategies can be employed. A common starting point is to implement a DMARC policy of 'p=none' to monitor email streams without rejecting emails. Analyzing DMARC reports is crucial to identify forwarding patterns and potential authentication issues. Recipient education is vital, encouraging them to forward emails as attachments or use methods that preserve headers. Alternative communication channels like SMS or web-based alerts can bypass email authentication problems altogether. On the technical side, ARC (Authenticated Received Chain) can help preserve authentication across multiple hops, and DKIM signing ensures email integrity. SPF flattening can prevent SPF record lookup limits. Regular infrastructure audits and a combination of SPF, DKIM, and DMARC are recommended to enhance overall email deliverability.

Experts emphasize the importance of comprehensive email authentication using SPF, DKIM, and DMARC across all email domains to prevent phishing. While ARC (Authenticated Received Chain) helps preserve authentication across forwarding chains, it's not a complete solution and requires careful investigation. Forwarding can also complicate List-Unsubscribe header handling, potentially causing unintended unsubscribes when authentication breaks, requiring careful configuration and an understanding of forwarding scenarios. BIMI (Brand Indicators for Message Identification) should be used to show your company logo.

Documentation highlights several approaches to handle DMARC failures due to forwarding. ARC (Authenticated Received Chain) is recommended for preserving authentication across intermediaries, allowing validation of original authentication. DMARC implementation should be phased, starting with a monitoring-only policy ('p=none') before moving to enforcement. SPF records need accurate configuration, including all legitimate sending sources. Microsoft 365 offers trusted forwarder configurations to maintain authentication for forwarded emails.